Meteorology Quiz: Breezes and Winds

Questions and Answers

What is a sea breeze?

A daytime breeze in which cooler air from high pressure over the coastal waters moves onshore to replace heated air rising above the warmer land mass.

What is a land breeze?

A light nighttime breeze which originates over the relatively cool land, flows out over the warmer coastal waters.

What are periods characterized as critical fire weather conditions? (Select all that apply)

High humidity

High temperature (correct)

Unstable atmosphere (correct)

Strong and shifting wind (correct)

What are common weather phenomena in which critical fire weather conditions occur? (Select all that apply)

Dust devils Signup and view all the answers

What is a cold front?

The boundary line between two different air masses, with cooler air behind the front and warmer air ahead of the front. Signup and view all the answers

What are potentially dangerous cold front characteristics? (Select all that apply)

Light southeasterly winds ahead of the front Signup and view all the answers

What are indicators of cold fronts? (Select all that apply)

Cumulus clouds approaching from W or NW Signup and view all the answers

What are foehn winds?

Strong, dry winds caused by the compression of air as it flows down the lee side of a mountain range. Signup and view all the answers

Which of the following is a common foehn wind in the Western US? (Select all that apply)

Sundowner wind Signup and view all the answers

Why are thunderstorms potentially dangerous to firefighters?

Winds can change direction and speed, leading to sudden changes in the rate and direction of a fire, and they can produce dangerous downdrafts and lightning. Signup and view all the answers

What are dust devils?

Common indicators of unstable air that occur on hot days over dry ground when skies are clear and the winds are light. Signup and view all the answers

What are firewhirls?

Generated by intense fires, firewhirls can pick up large burning embers and spread them across firelines. Signup and view all the answers

What are predictive services?

A combined group of Interagency Land Management Fire Intelligence Coordinators and Fire Meteorologists who provide seasonal assessments, fire potential outlooks, briefings, and daily summaries. Signup and view all the answers

What is the point of origin?

The precise location where a competent ignition source came into contact with the material first ignited and sustained combustion occurred. Signup and view all the answers

What is the head of a fire?

The side of the fire having the fastest rate of spread. Signup and view all the answers

What does the flank of a fire refer to?

The part of a fire's perimeter that is roughly parallel to the main direction of spread. Signup and view all the answers

What is meant by the rear of a fire?

Portion of a fire spreading directly into the wind or downslope; opposite the head and the slowest spreading portion of a fire edge. Signup and view all the answers

What are the three main objectives to fight a fire?

Anchor, Flank, Pinch. Signup and view all the answers

What is the fire perimeter?

Entire outer edge of a fire. Signup and view all the answers

What are fingers of a fire?

Long narrow extensions of a fire projecting from the main body. Signup and view all the answers

What are pockets of a fire?

Unburned indentations in the fire edge formed by fingers or slow burning areas. Signup and view all the answers

What is an island in the context of wildland fire?

Area of unburned fuel inside the fire perimeter. Signup and view all the answers

What is a spot fire?

Fire ignited outside the perimeter of the main fire by a firebrand. Signup and view all the answers

What does smoldering refer to in fire behavior?

Fire burning without flame and barely spreading. Signup and view all the answers

What is creeping fire?

Fire burning with a low flame and spreading slowly. Signup and view all the answers

What characterizes running fire?

Behavior of a fire spreading rapidly with a well-defined head. Signup and view all the answers

What does spotting in wildland fire behavior mean?

Behavior of a fire producing sparks or embers that are carried by the wind and which start new fires beyond the zone of direct ignition by the main fire. Signup and view all the answers

What is torching in regard to fire behavior?

The burning of foliage of a single tree or a small group of trees from the bottom up. Signup and view all the answers

What defines crown fire?

Fire that advances from top to top of trees or shrubs more or less independent of surface fire. Signup and view all the answers

What is a flare up in fire behavior?

Any sudden acceleration in the rate of spread or intensification. Signup and view all the answers

What is a firewhirl?

Spinning vortex column of ascending hot air and gases rising from a fire and carrying aloft smoke, debris, and flame. Signup and view all the answers

What is the backing fire?

That portion of the fire with slower rates of spread; also called the heel. Signup and view all the answers

What is the flaming front of a fire?

That zone of a moving fire where the combustion is primarily flaming. Signup and view all the answers

What is an anchor point in fire control?

An advantageous location, usually a barrier to fire spread, from which to start constructing a fireline. Signup and view all the answers

What is a control line in wildfire management?

An inclusive term for all constructed or natural barriers and treated fire edges used to contain a fire. Signup and view all the answers

What is a fireline?

The part of a containment or control line that is scraped or dug to mineral soil. Signup and view all the answers

What does mop-up entail in fire control?

Extinguishing or removing burning material near control lines. Signup and view all the answers

What does it mean when a fire is contained?

The status of a wildfire suppression action signifying that a control line has been completed around the fire. Signup and view all the answers

What does a controlled fire imply?

The completion of control line around a fire, any spot fires, and any interior islands to be saved. Signup and view all the answers

1 chain = ____ feet.

66 Signup and view all the answers

What are the three elements of the fire triangle?

Fuel to burn, air to supply oxygen for the flame, heat to start and continue the combustion process. Signup and view all the answers

What are the three methods of heat transfer?

Radiation, convection, conduction. Signup and view all the answers

What is radiation in the context of fire behavior?

Radiant heat can dry surrounding fuels and sometimes ignite them. Signup and view all the answers

Define convection as it relates to fire.

Occurs when lighter warm air moves upward. Signup and view all the answers

What is conduction in terms of fire behavior?

Heat is conducted from one fuel particle to another by direct contact. Signup and view all the answers

A fire is controlled when it is expected to hold under any foreseeable conditions.

True Signup and view all the answers

What does topography refer to?

The configuration of the earth's surface including its relief and the position of its natural and man-made features. Signup and view all the answers

What is aspect in terms of fire behavior?

The direction a slope is facing, its exposure in relation to the sun. Signup and view all the answers

What are the characteristics of a north facing slope?

Lower rate of spread, more shade, later snow melt, higher humidity, lower temperatures. Signup and view all the answers

What does slope refer to in wildfire context?

The amount or degree of incline of a hillside. Signup and view all the answers

How do box canyons affect fire behavior?

Fires starting near the base may react similar to a fire in a wood-burning stove or fireplace. Signup and view all the answers

What are narrow canyons' effects on fire behavior?

Fires can easily spread to fuels on the opposite side by radiation and spotting. Signup and view all the answers

What does elevation refer to?

The height of the terrain above mean sea level. Signup and view all the answers

What are barriers in the context of wildfire?

Any obstruction to the spread of fire, typically an area or strip lacking any flammable fuel. Signup and view all the answers

What three characteristics of fuel does fire behavior depend on?

Fuel type, fuel loading, fuel availability. Signup and view all the answers

What are the fuel types?

Grass, Grass-Shrub, Shrub, Timber-Understory, Timber Litter, Slash-Blowdown. Signup and view all the answers

What defines fuel loading?

The amount of fuel present expressed quantitatively in terms of weight of fuel per unit area. Signup and view all the answers

What are the fuel size classes?

1-hr fuels: 0-.25 inch; 10-hr fuels: .25-1 inch; 100-hr fuels: 1-3 inches; 1000-hr fuels: 3-8 inches. Signup and view all the answers

How does surface area to volume ratio relate to fire behavior?

Smaller fuels have a high surface area to volume ratio, leading to longer-lasting burn times. Signup and view all the answers

What does fuel arrangement refer to?

The manner in which fuels are spread over a certain area. Signup and view all the answers

What are ground fuels?

All combustible materials lying beneath the surface. Signup and view all the answers

What are surface fuels?

All combustible materials lying on or immediately above the ground. Signup and view all the answers

What are ladder fuels?

Combustible materials that aid the spread of fire from the surface to the upper canopy. Signup and view all the answers

What are aerial fuels?

All green and dead materials located in the upper canopy. Signup and view all the answers

What is fuel moisture?

The amount of water in a fuel, expressed as a percentage of the over-dry weight of that fuel. Signup and view all the answers

What does a stable atmosphere refer to?

An atmosphere that resists upward motion. Signup and view all the answers

What are visual indicators of an unstable atmosphere?

Clouds grow vertically, and smoke rises to great heights. Signup and view all the answers

What is the jet stream?

Large scale upper level winds caused by high and low pressure systems. Signup and view all the answers

What are local winds?

Winds developed when skies are clear and general winds are weak, influenced by terrain. Signup and view all the answers

How do upslope winds behave?

Speed generally ranges from 3-8 mph and can be gusty. Signup and view all the answers

What characterizes downslope wind?

Air cools and sinks producing downsloping winds, greatest flow occurs after midnight. Signup and view all the answers

What influences wind characteristics in valleys?

Temperature and pressure differences result in wind flow, affecting fire behavior. Signup and view all the answers

Study Notes

Wildland Fire Behavior Terminology

Point of origin: Exact place of initial ignition where combustion begins.
Head of a fire: Fastest spreading side of a fire.
Flank of a fire: Area adjacent to the main direction of fire spread.
Rear of a fire (heel): Slowest portion, spreading against the wind or downhill.
Fire perimeter: Total outer edge of a fire.
Fingers of a fire: Narrow extensions extending from the main fire body.
Pockets of a fire: Unburned areas within fire edge, surrounded by fingers or slower burning sections.
Island: Unburned fuel zone inside fire perimeter.
Spot fire: New fire ignited outside the main fire perimeter by embers.
Smoldering: Fire behavior characterized by no flame and minimal spread.
Creeping fire: Slow-spreading fire with low flames.
Running fire: Rapidly spreading fire with a clear head.
Spotting: When fire sends sparks or embers beyond its main ignition zone.
Torching: Ignition of leaves/foliage of trees from the bottom, typically small groups.
Crown fire: Fire reaching the tops of trees, may be independent of surface fire.

Fire Behavior and Control

Flare up: Sudden increase in fire spread or intensity, often short-lived.
Firewhirl: Vertical vortex of heated air, smoke, and gases from a fire, unpredictable in movement.
Anchor point: A barrier to fire spread used as a starting position for fireline construction.
Control line: All constructed or natural barriers plus treated fire edges for containment.
Fireline: Area of the control line that has been cleared down to mineral soil.
Mop-up: Procedure of extinguishing near control lines to prevent flare-ups.
Contained: Fire status indicating that control lines are complete, expecting to prevent spread.
Controlled: Completion of control lines around the fire, including buffers to manage hot spots.

Fire Triangle and Heat Transfer

Three elements of the fire triangle: Fuel, air (oxygen), and heat.
Three methods of heat transfer: Radiation, convection, and conduction.
Radiation: Heat that can dry or ignite surrounding fuels.
Convection: Upward movement of warm air and embers creating a smoke column.
Conduction: Heat transfer through direct contact between fuel particles.

Topography's Role in Fire

Topography: Arrangement of the earth's features, affecting fire spread.
Aspect: Slope direction regarding sun exposure; influences fuel moisture and fire behavior.
Box canyons: Fires in these areas can have accelerated reactions similar to flames in enclosed spaces.
Narrow canyons: Eddies and strong winds can spread fire across to opposing sides.
Ridges: Fire may change direction when ridges meet canyons due to airflow.
Saddle: Wind through mountain passes increases speed and may cause erratic fire behavior.

Fuel Dynamics

Fuel characteristics affecting fire behavior: Type, loading, and availability.
Fuel types: Grass, grass-shrub, shrub, timber-understory, timber litter, and slash-blowdown.
Fuel loading: Weight of fuel per unit area, indicating potential intensity and spread.
Surface Area to Volume Ratio: Smaller fuels burn quicker due to higher surface area exposed to air.
Fuel arrangement: The spatial distribution of fuels; can be horizontal or vertical, affecting fire spread.
Vertical arrangement: Includes ground, surface, ladder, and aerial fuels, contributing to fire intensity.
Fuel moisture: Determines ignitibility and burning efficiency, affected by weather conditions.

Weather and Fire Behavior

Fire weather principles: Temperature, relative humidity, precipitation, atmospheric stability, and wind patterns.
Relative humidity (RH): Levels inversely related to temperature; affects fuel moisture.
Atmospheric stability: Influences upward air movement; unstable conditions promote fire intensity.
Indicators of stable and unstable atmospheres: Variations in cloud formation, visibility, and wind patterns often signal fire behavior changes.
Critical fire weather conditions: Strong winds, low humidity, high temperature, and dry thunderstorms can trigger severe fire risks.

Wind Effects on Wildland Fires

General winds: Larger scale, resulting from atmospheric pressure systems, usually flowing west to east.
Local winds: Terrain-influenced winds including upslope and downslope variations.
Specific wind characteristics: Variability in speed and direction throughout the day significantly impacts fire dynamics.### Weather and Fire Risks
Warm conditions for the season can lead to increased fire risk.
Winds can persist for several days, often reaching speeds of 40-60 mph.
Relative humidity (RH) decreases as winds pick up.
High wind speeds combined with low RH create ideal conditions for rapid fire spread.

Common Foehn Winds in the Western US

Chinook Wind: Found along the eastern Rockies and east of Sierra Nevada.
Wasatch Wind: Occurs on the western side of the Wasatch Range in Utah.
Santa Ana and Sundowner Winds: Affect Southern California.
Mono and North Wind: Influence central and northern California.
East Wind: Present in western Washington and western Oregon.

Thunderstorm Risks for Firefighters

Winds associated with thunderstorms can shift, altering fire behavior and intensity.
Rising heat from fires can create strong convection columns, potentially forming thunderstorms.
Thunderstorms can produce hazardous downdrafts, increasing fire danger.
Lightning strikes pose additional risks for igniting new fires.

Dust Devils

Serve as indicators of unstable air conditions in hot, dry weather.
They typically form over dry ground on clear days with light winds.

Firewhirls

Generated by intense heat from wildfires.
Capable of lifting large, burning embers and spreading them beyond the main fireline, causing new spot fires.
Often develop on the leeward side of ridges, where winds are sheltered.

Predictive Services

Comprise a team of Interagency Land Management Fire Intelligence Coordinators and Fire Meteorologists.
Conduct seasonal assessments to evaluate fire risks.
Provide forecasts for 7-day significant fire potential and monthly outlooks.
Offer briefings and daily summaries to inform firefighting efforts.

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Description

Test your knowledge on different types of breezes, including sea and land breezes. Understand the conditions that create these daytime and nighttime winds, and explore their speeds and characteristics. This quiz covers essential concepts in meteorological phenomena.